The invention relates to a motor vehicle wind deflector for sliding roofs, removable roof sections or the like, wherein the wind deflector is arranged adjacent to a transversely extending front edge of the roof cut-out for the movable roof and is movable from a recessed stored inoperative position into a moved-out, erected operative position.
From DE-OS 34 15 361, a motor vehicle having a sliding roof and a pivotable wind deflector is known. Here, after opening of the sliding roof, a wind deflector, which is arranged adjacent to the transversely extending front edge area of the roof section, automatically takes up a moved-out erected operative position. Tests with vehicles of this type have shown that during the driving operation when the sliding roof is open, disturbing vibrations occur in the vehicle interior despite the tilted-out wind deflector. These vibrations become noticeable as noises, pressure in the ears, or rattling of doors and windows. These vibrations (which are also called sliding roof rumbling) differ from one vehicle to the next. They depend on, among other things, the shape of the roof, the ventilation of the interior, the size of the roof cut-out and the driven speed of the vehicle.
The vibrations are caused by the fact that the air flow guided over the vehicle roof breaks off at the transversely extending front edge of the roof cut-out, or at the wind deflector. Also, at a slow driving speed, wind does not overcome the roof cut-out but flows into the vehicle interior located below it. However, at the same time, as a result of the increased flow velocity above the roof cut-out, an under pressure is generated in the vehicle interior which seeks to take in air through the cut-out. Both flows cause disturbing turbulences which happen in a periodically alternating manner. As a result, a pulsating (close to resonance frequency) of an air column takes place in the vehicle interior which becomes extremely annoying (E.G. noise, pressure in the ears, etc.).
It is the object of the invention to avoid the occurrence of these disturbing vibrations (sliding roof rumbling) in the vehicle interior in motor vehicles having a sliding roof and a wind deflector during open roof driving operations.
According to the invention, this object is achieved by providing at least one additional air guiding element of narrow width, arranged locally at the wind deflector. This air guiding element projects beyond this wind deflector in an upward direction in the operative position of the wind deflector.
It is also advantageous if the air guiding element is preferably provided adjacent to a longitudinal center plane of the motor vehicle. The width of the air guiding element should amount to at least 1/10 of the width of the roof cut-out. The overall height from the front edge of the roof cut-out to an upper edge of the moved-out air guiding element should amount to at least 1/7 of the length of the roof cut-out. The length of the additional air guiding element must amount to at least 1/10 of the length of the roof cut-out.
It is also advantageous if the air guiding element is adjusted more steeply than the wind deflector, with the angle of difference amounting to approximately 30 degrees. The air guiding element can be firmly or flexibly connected with the wind deflector and can be moved from a moved-in retracted position into a moved-out extended position and vice-versa.
The wind deflector can be formed by a profiled sheet metal part with a depression directed toward the vehicle interior in the area of the air guiding element for accommodating the moved-in air guiding element. The flexible connection for the air guiding element may be created by way of a horizontally aligned, transversely extending shaft, flexibly connected with the wind deflector and with spring elements moving the air guiding element in a tilt-out direction about the shaft.
It is also desirable if a support area is provided at the wind deflector adjacent to its free end for limiting the operative position of the air guiding element as it is positioned relative to the deflector. The wind deflector is provided with an end-side lengthening extension adjacent to this support area. This extension is in alignment with the course of the shape of the wind deflector.
To assist retraction of the air guide element a guide shoe is mounted at a front edge of a cover. This guide shoe moves the air guiding element into the retracted moved-in position as the cover is closed.
The principal advantages achieved by the invention, as a result of the arrangement of an additional air guiding element having a narrow width at the wind deflector, is an elimination of disturbing vibrations in the vehicle interior. Preferably, the air guiding element which, in the operative condition, projects beyond the wind deflector in upward direction, is arranged adjacent to a longitudinal center plane of the motor vehicle. Over the course of its width, the air guiding element deflects the flow at a higher level so that the roof cut-out is overcome. On both sides of the air guiding element, the air, in addition, is also moved over the roof cut-out. In the laterally exterior zones of the roof cut-out, the flow is almost unaffected by the additional air guiding element, but it can no longer combine to form the large periodic alternations. The additional air guiding element therefore interferes with the formation of turbulences, divides them and prevents the periodic vibrating of the air column in the vehicle interior.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.